Rat Salivary Glands Research Articles

Evaluation of non-invasive biomonitoring of 2,4-Dichlorophenoxyacetic acid (2,4-D) in saliva

The objective of this study was to evaluate the potential for non-invasive biomonitoring of 2,4-Dichlorophenoxyacetic acid (2,4-D) in saliva. Using an in vitro rat salivary gland epithelial cell (SGEC) system, a collection of experiments investigating chemical protein binding, temporal and directional transport, as well as competitive transport with para-aminohippuric acid (PAH), a substrate for renal organic anion transporters, was conducted to identify cellular transport parameters required to computationally model salivary transport of 2,4-D. Additionally, a physiological protein gradient was implemented to mimic physiologically relevant concentrations of protein in rat plasma and saliva, and under these conditions the transfer of 2,4-D was markedly slower, driven by increased protein binding (i.e. reduced free 2,4-D species available to cross salivary barrier). The rate of transfer was directly proportional to the amount of unbound 2,4-D and demonstrated no indication of active transport. An in vivo assessment of 2,4-D exposure in rats revealed non-linear protein binding in plasma, indicating saturated protein binding and increased levels of unbound 2,4-D species at higher doses. A strong correlation between 2,4-D concentrations in saliva and unbound 2,4-D in plasma was observed (Pearson correlation coefficient = 0.95). Saliva:plasma 2,4-D ratios measured in vivo (0.0079) were consistent within the linear protein binding range and expected 2,4-D levels from occupational exposures but were significantly different than ratios measured in vitro (physiological conditions) (0.034), possibly due to 2,4-D concentrations in saliva not being at equilibrium with 2,4-D concentrations in blood, as well as physiological features absent in in vitro settings (e.g. blood flow). We demonstrated that 2,4-D is consistently transported into saliva using both in vitro and in vivo models, making 2,4-D a potential candidate for human non-invasive salivary biomonitoring. Further work is needed to understand whether current sensor limits of detection are sufficient to measure occupationally relevant exposures.

The apoptotic effect of midazolam on the salivary gland of rats and the reversal effect by pilocarpine.

To evaluate the apoptosis in parotid glands of rats treated with midazolam associated or not with pilocarpine, 60 Wistar rats were assigned to 6 groups: control groups received saline solution for 30 days (S30) and 60 days (S60) and the other groups received pilocarpine for 60 days (P60), midazolam for 30 days (M30), midazolam for 30 days and 30 days of saline (M30 + S30), and finally midazolam for 30 days and 30 days of midazolam and pilocarpine (M30 + MP30). Histological sections were subjected to the TdT-mediated dUTP-biotin nick and labeling technique. The number of positive and negative cells was quantified, calculating the apoptotic index. ANOVA at 2 criteria and Tukey's test were used. A greater apoptotic index was observed in the M30 (52.79 ± 9.01) and M30 + S30 (62.43 ± 8.52) groups when compared with the S30 (37.94 ± 5.94) and S60 (31.85 ± 9.18) groups, respectively (p < 0.05). There was no difference between M30 + MP30 (30.98 ± 6.19) and S60 (31.85 ± 9.18) groups regarding apoptotic index. Chronic administration of midazolam has been shown to increase the number of apoptotic cells in the parotid glands of rats. However, pilocarpine inhibited this effect, thus inhibiting the apoptosis.

Prosaposin and its receptors are differentially expressed in the salivary glands of male and female rats.

Salivary glands produce various neurotrophins that are thought to regulate salivary function during normal and pathological conditions. Prosaposin (PSAP) is a potent neurotrophin found in several tissues and various biological fluids and may play roles in the regulation of salivary function. However, little is known about PSAP in salivary glands. As the functions of salivary glands are diverse based on age and sex, this study examines whether PSAP and its receptors, G protein-coupled receptor 37 (GPR37) and GPR37L1, are expressed in the salivary glands of rats and whether sex and aging affect their expression. Immunohistochemical analysis revealed that PSAP and its receptors were expressed in the major salivary glands of rats, although their expression varied considerably based on the type of gland, acinar cells, age and sex. In fact, PSAP, GPR37 and GPR37L1 were predominantly expressed in granular convoluted tubule cells of the submandibular gland and the intensity of their immunoreactivity was higher in young adult female rats than age-matched male rats, which was more prominent at older ages (mature adult to menopause). On the other hand, weak PSAP, GPR37 and GPR37L1 immunoreactivity was observed mainly in the basal layer of mucous cells of the sublingual gland. Triple label immunofluorescence analysis revealed that PSAP, GPR37 and GPR37L1 were co-localized in the basal layer of acinar and ductal cells in the major salivary glands. The present findings indicate that PSAP and its receptors, GPR37 and GPR37L1, are expressed in the major salivary glands of rats and their immunoreactivities differ considerably with age and sex.

EFFECT OF NEOSTIGMINE ADMINISTRATION ON THE ULTRASTRUCTURE OF THE PAROTID SALIVARY GLAND IN RATS WITH INDUCED DIABETES

Introduction:Neostigmine is parasympathomimetic drug. It is commonly used for treatment of myasthenia gravis, glaucoma, urinary retention, xerostomia, and post-operative ileus. Parasympathomimetic drugs increase the rate of salivation. Dry mouth is a frequent clinical complain among diabetic patients. Objectives:The present study is designed to investigate the effect of neostigmine administration on the ultrastructure of the parotid salivary gland in rats with induced diabetes. Materials and methods: Twenty one adult male rats were divided into three equal groups (seven rats each) Group I: Control group, Group II: Induced diabetes group (with no treatment), Group III: Induced diabetes group (with Therapeutic doses of Neostigmine which were administered intramuscularly every other day for one month. Diabetes was induced by a single intravenous injection of Streptozotocin. After one month all rats were sacrificed and the parotid glands were excised and processed for scanning electron microscopy. Histomorphometric analysis of the number of the intra-cellular vacuoles was done, and the data obtained were statistically analyzed. Results There was a statistically significant difference between the studied groups regarding the diameter of secretory granules, as it was increased in neostigmine treated group and decreased in diabetic group. Also there was restoration of the density and organization of the nerve distribution adjacent to secretory acini in neostigmine treated group. Conclusions: The ultrastructural findings noticed in this study substantiate the use of Neostigmine in cases of diabetes associated xerostomia.

Морфологічні перебудови привушної слинної залози щурів при експериментальному зневодненні організму та застосуванні вітаміну Е

Морфологічні перебудови привушної слинної залози щурів при експериментальному зневодненні організму та застосуванні вітаміну Е

Methylmercury Intoxication Promotes Metallothionein Response and Cell Damage in Salivary Glands of Rats.

Environmental and occupational mercury exposure is considered a major public health issue. Despite being well known that MeHg exposure causes adverse effects in several physiologic functions, MeHg effects on salivary glands still not completely elucidated. Here, we investigated the cellular MeHg-induced damage in the three major salivary glands (parotid, submandibular, and sublingual) of adult rats after chronic, systemic and low doses of MeHg exposure. Rats were exposed by 0.04mg/kg/day over 60days. After that, animals were euthanized and all three glands were collected. We evaluated total Hg accumulation, metallothionein I/II (MT I/II), α-smooth muscle actin (α-SMA), and cytokeratin 18 (CK18) immune expression. Our results have showed that MeHg is able to disrupt gland tissue and to induce a protective mechanism by MT I/II expression. We also showed that cell MT production is not enough to protect gland tissue against cellular structural damage seen by reducing marking of cytoskeletal proteins as CK18 and α-SMA. Our data suggest that chronic MeHg exposure in low-daily doses is able to induce cellular damage in rat salivary glands.

Analiza 3D slike minornih pljuvačnih žlezda kod pacova rođenih sa makrozomijom i starih 180 dana

Objective. To determine the morphometric differences in the minor buccal salivary glands in rats aged 6 months with fetal macrosomia (groups under study) and in rats aged 6 months after a normal intrauterine development (control group) by using a 3-D analysis technique. Methods. The fetal macrosomia was induced in four different ways. To apply the morphological analysis, the tissues of oral cavity mucosa of six-month-old rats were used. The 3-D images acquired by confocal microscopy were used for estimating the morphometrical characteristics of minor buccal salivary gland microscopic structures. Results. On reaching the age of six months, the descendants of the rats in all macrosomic groups have the average body weight, the average body length, and the average weight-to-length ratio comparable to those in the Control Group. In rats born with different fetal macrosomia modeling, when the age of 6 months was reached, the deviations in the Groups under study from the Control Group were found to appear to various degree in the following parameters: the acinus area, the acinus gap area, the number of mucous acinar cells in the acinus, the height of the cytoplasm of mucous acinar cells, and the percentage fractions of the relative area of mucous acinar cells cross-sections, area of acinar gap cross-sections and relative area of glandular stroma. Conclusion. The clustered technique assessment of these deviations brings us to the conclusion about the presence of hypoplasia of minor buccal salivary glands in rats born with fetal macrosomia.

Иммуногистохимические особенности больших слюнных желез крыс при экспериментальном пародонтите

Иммуногистохимические особенности больших слюнных желез крыс при экспериментальном пародонтите

Electrophysiological study on sensory nerve activity from the submandibular salivary gland in rats

To evaluate the role of afferent information from the salivary gland, we analyzed the neural activity of the sensory nerve innervating the submandibular gland in anesthetized rats. The sensory nerves running through the parasympathetic nerve supply responded to mechanical pressure applied to the surface of the main duct and the body of the gland, whilst those in the sympathetic nerve supply responded only to the body of the gland. The sensory nerves in the sympathetic and parasympathetic nerve routes responded to pressure in the duct system produced by a retrograde injection of saline into the main duct. The threshold pressure for production of afferent discharges was higher than the maximum secretory pressure evoked by electrical stimulation of the parasympathetic secretory nerve. The retrograde ductal injection of drugs related to the inflammatory process (capsaicin and bradykinin) evoked intense multi-unit discharges in the sensory nerves of both routes. The sensory nerve in the sympathetic route was responsive to ligation of the artery to the gland. These results suggest that sensory nerves in the sympathetic and parasympathetic routes mainly conduct noxious information, and that those in the sympathetic route are responsive to ischemia and may control blood flow of the gland.

Lysosomal Exoglycosidase Profile and Secretory Function in the Salivary Glands of Rats with Streptozotocin-Induced Diabetes.

Before this study, there had been no research evaluating the relationship between a lysosomal exoglycosidase profile and secretory function in the salivary glands of rats with streptozotocin- (STZ-) induced type 1 diabetes. In our work, rats were divided into 4 groups of 8 animals each: control groups (C2, C4) and diabetic groups (STZ2, STZ4). The secretory function of salivary glands—nonstimulated and stimulated salivary flow, α-amylase, total protein—and salivary exoglycosidase activities—N-acetyl-β-hexosaminidase (HEX, HEX A, and HEX B), β-glucuronidase, α-fucosidase, β-galactosidase, and α-mannosidase—was estimated both in the parotid and submandibular glands of STZ-diabetic and control rats. The study has demonstrated that the activity of most salivary exoglycosidases is significantly higher in the parotid and submandibular glands of STZ-diabetic rats as compared to the healthy controls and that it increases as the disease progresses. Reduced secretory function of diabetic salivary glands was also observed. A significant inverse correlation between HEX B, α-amylase activity, and stimulated salivary flow in diabetic parotid gland has also been shown. Summarizing, STZ-induced diabetes leads to a change in the lysosomal exoglycosidase profile and reduced function of the salivary glands.

Chronic intoxication by methylmercury leads to oxidative damage and cell death in salivary glands of rats.

Methylmercury (MeHg) is one of the most toxic species of mercury, causing several systemic damages; however, its effect on the salivary glands has rarely been explored to date. This study was aimed at analyzing the mercury deposit, oxidative stress markers, and cell viability in parotid and submandibular rat salivary glands after chronic methylmercury intoxication. Herein, forty male Wistar rats (40 days old) were used in the experiment. The animals of the experimental group were intoxicated by intragastric gavage with MeHg at a dose of 0.04 mg per kg body weight per day for 35 days, whereas the control group received only corn oil, a diluent. After the period of intoxication, the glands were obtained for evaluation of total mercury deposit, cell viability, and the malondialdehyde (MDA) and the nitrite levels. Our results indicated mercury deposits in salivary glands, with a decrease in cell viability, higher levels of MDA in both glands of intoxicated animals, and a higher concentration of nitrite only in the submandibular gland of the mercury group. Thus, the intoxication by MeHg was able to generate deposits and oxidative stress in salivary glands that resulted in a decrease in cell viability in both types of glands.

Chronic exposure to inorganic mercury induces biochemical and morphological changes in the salivary glands of rats.

Mercury exposure is considered to be a public health problem due to the generation of toxic effects on human health as a result of environmental and occupational conditions. The inorganic form of mercury (HgCl2) can cause several biological changes in cells and tissues through its cumulative toxic potential, but little has been experimentally proven about the effects of inorganic mercury on salivary glands, an important modulator organ of oral health. This study analyzes the effects of prolonged low dose exposure to HgCl2 on the salivary glands of rats. Adult animals received a dose of 0.375 mg kg-1 day-1 over a period of 45 days. The parotid and submandibular glands were collected for analysis of the mercury levels and evaluation of oxidative stress, histological parameters and immunomodulation for metallothionein I and II (MT-I/II). In this investigation, biochemical and tissue changes in the salivary glands were verified due to the mercury levels, causing reduction in antioxidant capacity against peroxyl radicals, with consequent cellular lipid peroxidation and an increase in nitrite levels, volumetric changes and cytoskeletal damage in the submandibular glands, with less severe damage to the parotid glands. The results also have shown the occurrence of a cytoprotection mechanism due to increased MT-I/II expression, but not enough to avoid the morphology and oxidative damage. This evidence highlights, for the first time, that inorganic mercury is able to alter the morphology and oxidative biochemistry in salivary glands when exposed for a long time in low doses.

Localization and expression patterns of TRP channels in submandibular gland development

ObjectiveExpression of Transient receptor potential (TRP) channels: TRP canonical (TRPC)1, TRP vanilloid (TRPV)3, TRPV4 and TRP melastatin (TRPM)8 in adult rat salivary gland has recently been reported. The authors investigated expression of these TRP channels in the submandibular gland during early developmental stage in which the cell constitution is different, and discussed the function of TRP in the submandibular gland in early development. DesignUsing rat submandibular gland at embryonic days (E)18 and E20 and postnatal days (PN)0 and PN5 and PN28, expression of TRPV3, TRPV4, TRPC1 and TRPM8 was investigated using real-time polymerase chain reaction (RT-PCR) and immunohistochemistry. ResultsAll TRP channels were expressed in cells constituting the submandibular gland in early developmental stage, but an increase in the expression level at PN5 on RT-PCR was significant compared with those at E18, PN0 and PN28 in TRPC1 and TRPV4 channels, whereas an increase was observed but not significant in the others. On immunohistochemical staining at PN5, whereas strong reactions of anti-TRPM8 antibody, anti-TRPV3 and anti-TRPV4 antibodies were observed in cells which proliferated from a terminal portion of cells arranged tubular structure which previously constituted mostly the submandibular gland. ConclusionIt was clarified that TRP channels are expressed in the rat submandibular gland in early developmental stage although cells constituting the submandibular gland are different from those in adult animals, suggesting that these TRP channels are involved in cell differentiation in at PN5 into the adult submandibular gland during early development.

BIOLOGICAL IMPACT OF CINNAMON EXTRACT VS. DIAZEPAM ON SUBMANDIBULAR SALIVARY GLANDS OF STRESSED ALBINO RATS.

31Oct 2016 BIOLOGICAL IMPACT OF CINNAMON EXTRACT VS. DIAZEPAM ON SUBMANDIBULAR SALIVARY GLANDS OF STRESSED ALBINO RATS. Elham Hassan Hassan , Laila Elsayed Amin , Mohamed I. Mourad and Heba Mahmoud Elsabaa. Demonstrator of Oral Biology, Faculty of Dentistry, Mansoura University, Egypt. Lecturer of Oral Biology, Faculty of Dentistry, Mansoura University, Egypt. Lecturer of Oral Pathology, Faculty of Dentistry, Mansoura University, Egypt. Professor of Oral Biology, Faculty of Dentistry, Mansoura University, Egypt.

Effect of streptozotocin-induced diabetes on lipids metabolism in the salivary glands

BackgroundDiabetes is one of the most common metabolic diseases. Moreover, previous studies indicate that diabetes may cause changes in the salivary glands phenotype and in the composition of saliva itself. Therefore, the main objective of this study was to determine the effects of streptozotocin induced diabetes on lipid profile of the rat salivary glands. MethodsMale Wistar rats were divided into two groups: control and STZ-induced diabetes. At the end of the experiment all animals were sacrificed and samples of the parotid and submandibular salivary glands were excised. Major lipid fractions concentrations were determined by means of chromatography (TLC and GC). ResultsWe observed a significant increase (∼3.5 fold) in the level of triacylglycerol in both the parotid and submandibular salivary glands of diabetic rats. The abovementioned changes were accompanied by significant, although less dramatic (i.e. from −60% to −90%), decrements in the levels of other lipid classes (phospholipids, free fatty acids and diacylglycerol). ConclusionsIn our study we have showed, presumably for the first time, that streptozotocin induced diabetes causes decrement in PH content with subsequent atrophy and malfunction in both parotid and submandibular salivary glands. Another novel finding of our research is that diabetic rats were characterized by an increased TG accumulation in both parotid and submandibular salivary glands. The later one could be a clinical manifestation of diabetes.

The protective effects of different treatments on rat salivary glands after radiotherapy.

This study was aimed to evaluate the efficacy of treatment modalities for minimizing salivary gland damage caused by radiotherapy. Forty rats were divided into five groups. Group 1 had no irradiation or any treatment. Group 2 underwent only 15Gy single dose radiotherapy. N-acetylcysteine, dexamethasone, hyperbaric oxygen treatment were given, respectively to the group 3, 4 and 5 for 5days. 15Gy single dose radiotherapy was applied to the group 3, 4 and 5 on the second day. Pyknosis, lysis, and vacuolization were examined in ductal cells and pyknosis, lysis, vacuolization, inflammation and collective duct damage in acinar cells. Dexamethasone and hyperbaric oxygen did not prove to have a positive effect on acinar and ductal cell. N-acetylcysteine-applied group had statistically significantly lower amount of damage. We determined that the decrease of ductal and acinar cell damage in parotid glands of N-acetylcysteine-applied rats was more distinct and statistically.

Histological and immunohistochemical study on the possible ameliorating effects of thymoquinone on the salivary glands of rats with experimentally induced hypothyroidism

BackgroundAlthough the physiological and biochemical effects of hypothyroidism on salivary glands were frequently studied in previous research, its histological aspects have not been sufficiently studied.AimThis study aimed to assess the histopathological changes caused by experimentally induced hyp

Functional Expression of a Ca(2+)-activated Cl(-) Channel Modulator Involved in Ion Transport and Epithelial Cell Differentiation

Cl(-)-permeable channels and transporters expressed on the cell membranes of various mammalian cell types play pivotal roles in the transport of electrolytes and water, pH regulation, cell volume and membrane excitability, and are therefore expected to be useful molecular targets for drug discovery. Both TMEM16A (a possible candidate for Ca(2+)-regulated Cl(-) channels recently identified) and cystic fibrosis transmembrane conductance regulator (CFTR) (or cAMP-regulated Cl(-) channels) have been known to be involved in Cl(-) secretion and reabsorption in the rat salivary gland. Crosstalk between two types of regulatory pathways through these two types of channels has also been described. Previously, we demonstrated that CLCA, a Ca(2+)-activated Cl(-) channel modulator, was involved in Cl(-) absorption in rat salivary ducts. In addition to Ca(2+), basal NF-κB activity in a mouse keratinocyte line was shown to be involved in the transcriptional regulation of CLCA. Conversely, a truncated isoform of CLCA was found in undifferentiated epithelial cells present in the rat epidermal basal layers. Under regulation by Ca(2+) and PKC, the surface expression of β1-integrin and cell adhesion were decreased in the CLCA-overexpressing cells. Knockdown of this isoform elevated the expression of β1-integrin in rat epidermis in vivo. These results indicate that the specific differentiation-dependent localization of CLCA, and transcriptional regulation through Ca(2+), are likely to affect ion permeability and the adhesive potential of epithelial cells. In summary, these types of Cl(-) channels and their modulators may function in a coordinated manner in regulating the functions of epithelial cells under different physiological conditions.

DYNAMICS OF STRUCTURAL CHANGE OF MAJOR SALIVARY GLANDS AREA IN RATS IN THE NORM AND AFTER INTRAUTERINE ANTIGENIC ACTION

The research was aimed to determine the dynamic features of the area ratio between the secretory portions and connective tissue of the major salivary glands in rats after intrauterine antigenic action. Antigenpremium animals of the first day of postnatal development showed the imbalance in percentage distribution of the area between epithelial and connective tissue structures of salivary glands in comparison with newborn intact rats in the form of reliable reduction of the secretory portion percentage and increased area of the connective structures. Disorders in the ratio of the parts of investigated structures is preserved on the level of significant difference till the seventh day, on the level of tendency – till the fourteenth day and it practically disappeared on the fortyfifth day of postnatal life.

Characterization of Long-Term Cultured Murine Submandibular Gland Epithelial Cells

PurposeHuman and rat salivary gland cell lines derived from tumors or genetic modification are currently available for research. Here, we attempted to culture and characterize long-term cultured cells spontaneously derived from wild type murine submandibular glands (SGs).MethodsSGs were removed from 3-week-old C57B/6J female mice and dissociated by collagenase type 1 and hyaluronidase digestion. Isolated SG epithelial cells were cultured in low calcium, serum-free growth media in the presence of cholera toxin (CT) during early passages. Single-cell colonies were isolated by limiting dilution culture after 25 passages. Early- and late-stage cell cultures were characterized for keratin 14, keratin 18, α-smooth muscle actin, and p63 by immunostaining and quantitative real-time PCR analysis.ResultsSG epithelial cells cultured in optimized media maintained their proliferative ability and morphology for over 80 passages. Long-term cultured cells expressed keratin 14, keratin 18, and p63, indicative of an epithelial phenotype.ConclusionsEpithelial cells originating from wild type murine SGs could be cultured for longer periods of time and remain phenotypically similar to ductal basal epithelium.